1. Field Of The Invention
The present invention relates to an apparatus for converting paper webs to corrugated board. Specifically, the present invention relates to an apparatus for controlling the degree of wrap a web is permitted about a preheating cylinder.
2. Description Of The Prior Art.
In the fabrication of corrugated board from paper webs, it may be desirable to heat one or more of the constituent webs to a predetermined temperature prior to bonding or corrugating.
There are several reasons for web preheating such as that disclosed by K. B. Lord in U.S. Pat. No. 3,004,880 for curl correction and that disclosed by W. P. Sorenson in U.S. Pat. No. 3,694,927 for adhesive cure acceleration. Another reason may be to plasticize a polymer plastic coating on a paper wed for fusion bonding a liner with a corrugated medium web.
In any case, however, it is necessary to set the wrap control rollers to a desired, predetermined position about the preheating cylinder. Such predetermined positionment must be variable over a relatively large arc about the heating cylinder to gain the maximum heating surface over a minimum diameter cylinder. Such large spans of adjustment are necessary due to widely varying operating conditions such as speed, ambient temperature, moisture content of the paper web and melting properties of a plastic laminae.
For reasons of operator convenience and safety, it is also desirable that such wrap control rollers be set from a control station remote from the operating machinery.
Although remote index control over wrap control roll positionment about a preheating cylinder is known to prior art as evidenced by the U.S. Pat. discloure of K. B. Lord, supra, it is an objective of this invention to disclose a remote indexing control that responds at a predetermined rate in directly seeking correspondence with a select angular setting.
Another object of the present invention is to teach the construction of a remote controlled, powered indexing mechanism that is operative over a major circular arc less than 360.degree..
Another objective of the invention is to teach an index control mechanism that neither requires a distinct, operator instruction to reverse the drive power thereof nor requires the wrap control roller to traverse the full circumference of the preheating cylinder to reach the desired set position.
A still further object of the present invention is to teach an index control mechanism whereby the wrap control roller traverses only the smallest included angle between the starting position and a new setting position regardless of the rotational direction that needs to be taken to reach such new setting position.